Acta Phys. -Chim. Sin. ›› 2012, Vol. 28 ›› Issue (10): 2423-2435.doi: 10.3866/PKU.WHXB201208312

• PHYSICAL CHEMISTRY OF MATERIALS • Previous Articles     Next Articles

Two-Dimensional Nanostructures of Topological Insulators and Their Devices

LI Hui1,2, PENG Hai-Lin1, LIU Zhong-Fan1   

  1. 1 Centre for Nanochemistry (CNC), College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China;
    2 Key Laboratory of Solar Thermal Energy and Photovoltaic System of Chinese Academy of Sciences, Institute of Electrical Engineering, the Chinese Academy of Sciences, Beijing 100190, P. R. China
  • Received:2012-07-27 Revised:2012-08-31 Published:2012-09-26
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (51121091, 21173004, 11104003) and National Basic Research Program of China (2011CB921904).

Abstract:

Three-dimensional (3D) topological insulators are a new state of quantum matter that are insulating in the bulk but have current-carrying massless Dirac surface states. Nanostructured topological insulators, such as quasi-two-dimensional (2D) nanoribbons, nanoplates, and ultrathin films with extremely large surface-to-volume ratios, distinct edge/surface effects, and unique physicochemical properties, can have a large impact on fundamental research as well as in applications such as electronics, spintronics, photonics, and the energy sciences. Few-layer topological insulator nanostructures have very large surface-to-volume ratios that can significantly enhance the contribution of exotic surface states, and their unique quasi-2D geometry also facilitates their integration into functional devices for manipulation and manufacturing. Here, we present our recent results on the controlled growth of quasi-2D nanostructures of topological insulators, as well as their novel functional devices. High quality quasi-2D nanostructures of Bi2Se3 and Bi2Te3 topological insulators have been synthesized by vapor-phase growth. Ultra-thin nanoplates of the topological insulators with uniform thickness down to a single layer have been grown on various substrates, including conductive graphene. A facile, high-yield method has been developed for growing single-crystal nanoplate arrays of Bi2Se3 and Bi2Te3 with well-aligned orientations, controlled thickness, and specific placement on mica substrates by van der Waals epitaxy. A systematic spectroscopic study, including angle-resolved photoemission spectroscopy (ARPES), micro-Raman spectroscopy, and micro-infrared spectroscopy, was carried out to investigate the quasi-2D nanostructures of topological insulators. Pronounced Aharonov-Bohm (AB) interference effects were observed in the topological insulator nanoribbons, providing direct transport evidence of the robust, conducting surface states. Transport measurements of a single nanoplate device, with a high-k dielectric top gate, showed a significant decrease in the carrier concentration and a large tuning of the chemical potential with electrical gating. We also present the first experimental demonstration of near-infrared transparent flexible electrodes based on few-layer topological insulator Bi2Se3 nanostructures that was epitaxially grown on a mica substrate by van der Waals epitaxy. Topological insulator nanostructures show promise as transparent flexible electrodes because of their good near-infrared transparency and excellent conductivity, which is robust against surface contamination and bending. Our studies suggest that quasi-2D nanostructures of topological insulators show promise for future electronic and optoelectronic applications.

Key words: Topological insulator, Dirac fermion, Nanostructure, van der Waals epitaxy, Transparent flexible electrode

MSC2000: 

  • O641